1. Field of the Invention
The present invention relates to multi-conductor electrical connector cables having improved electromagnetic characteristics.
2. Statement of the Problem
Multi-conductor electrical connector cables, such as ribbon cables, harnesses, flexible printed circuits, etc., are used in virtually all electronic devices. Such multi-conductor electrical connector cables typically comprise a plurality of electrical conductors extending between two (or more) ends or connectors. Such multi-conductor electrical connector cables are used to conduct signals within and/or into and/or out of the device.
In order to achieve economies of scale, multi-conductor electrical connector cables are mass-produced. Mass-produced multi-conductor electrical connector cables, although readily available and relatively inexpensive, are available in a limited number of standard configurations. Thus, mass-produced multi-conductor electrical connector cables tend to be relatively inflexible in that they are available with a predetermined or standard number of conducting members or cables. For example, standard multi-conductor electrical connector cables are typically available with four, eight, sixteen and/or thirty-two conducting members. Thus, depending on the particular application in which a mass-produced multi-conductor electrical connector cable is utilized, there may be one or more conductors that are not utilized and do not carry signals.
Where a mutli-conductor electrical connector cable is carrying electrical signals having certain properties, such as, for example, a certain power level and/or frequency, a nearby or adjacent unused conductor member may undesirably radiate or receive electromagnetic energy. In effect, the unused conductor member undesirably acts as an antenna by radiating and/or receiving electromagnetic energy and/or radiation. Such electromagnetic radiation emitted or received by the unused electrical conductor or conductors of a multi-conductor electrical connector cable may result in interference. The electrical interference may undesirably affect or degrade the performance of other nearby electrical components and/or the device. In addition, the electrical interference may be picked up by other conductors of the multi-conductor electrical connector cable and be returned to the circuit that is generating the interfering signal.
One approach that has been used to address the above-described problem is to specially-design multi-conductor electrical connector cables for each specific application. Such specially-designed multi-conductor electrical connector cables remove unused conductors from the design of the multi-conductor electrical connector cable. However, custom designing a multi-conductor electrical connector cable for each and every application is costly and inefficient in terms of time and resource utilization. Omission of one or more conductors from an existing or standard multi-conductor electrical connector cable design may degrade the mechanical properties, e.g., strength and/or reliability, of the standard multi-conductor electrical connector cable.
A second approach that has been used is to provide the multi-conductor electrical connector cable with a jacket or cover made of a material that absorbs or shields electromagnetic radiation. This approach, however, is also costly and may not shield the multi-conductor electrical conducting members from each other. Further, this approach does nothing to address the issue of unutilized conductors within the multi-conductor electrical connector cable.
Therefore, what is needed in the art is a multi-conductor electrical connector cable having improved electromagnetic characteristics, including reduced sensitivity to and reduced emission of electromagnetic radiation.